One type of snap-action or tactile feedback keyboard currently in widespread use involves the use of a contoured element which performs both the snap-action or tactile feedback function and also effects electrical contact when the keyboard is actuated. The snap-action or tactile element may be either a contoured metal element or a contoured plastic element in a keyboard assembly. In the case of the metal elements, they are typically formed out of spring metal, and they may be formed as individual contoured discs or as a strip of contoured discs or curved metal strips. In the case of plastic snap-action elements, they are typically formed by thermocompressive molding of a monolithic plastic layer (such as Mylar polyester) which is formed to include a matrix of contoured tactile elements. In almost all cases, the tactile elements are enclosed in a molded plastic case. While some keyboard configurations are actuated by direct application of the actuating force (typically the finger of the keyboard user) to the contoured tactile element, many keyboard configurations have discrete keys in the keyboard case to which the actuating force is applied and through which the actuating force is delivered to activate the tactile element. The keys are typically molded plastic elements, and they may be of various constructions known in the art, such as living hinge keys, floating hinge keys and full floating keys.
Experience in the keyboard industry has shown that it is often desirable to have a striker of a specifically determined configuration on the bottom of the key to come into contact with the tactile element for actuating the tactile element. The particular shape and location of the striker is often important in achieving optimum or even satisfactory operation of the tactile element. Thus, for example, in some keyboards using metal discs, the striker on the bottom of the key is a hemispherical element which applied a point contact force to the contoured tactile element. Similarly, for some constructions using the plastic snap-action elements, the striker on the bottom of the key may be in the form of a bar to deliver a line of actuating force to the tactile element.
Heretofore, it has not generally been possible to obtain a high degree of interchangeability between keyboard components. For example, when a manufacturer has been using a keyboard with plastic case and keys and a metal dome, and the manufacturer decides he wants to use the same case and keys with tactile elements in the molded plastic sheet, he encounters the problem that the striker on the key for the metal element will not be suitable for the plastic tactile element. Therefore, the key must be redesigned, new molds may be required, and substantial additional expenses may be encountered. Also, if the manufacturer is going to use both types of tactile elements in different keyboard applications, then the manufacturer is faced with duplication or multiplication of requirements for tooling, inventory control and quality control.